1. Field of the Invention
The present invention relates to a rechargeable battery, and more particularly, to a rechargeable battery in which a protection circuit module is coupled with a bare cell.
2. Discussion of the Background
The use of rechargeable batteries is increasing due to their many advantages, including rechargeability, miniaturization, and increased charging capacity. A rechargeable battery can be classified as either a Ni-MH battery or a Li-ion battery, depending on the type of electrode active materials in the battery.
Generally, rechargeable batteries have bare cells manufactured by installing an electrode assembly with a positive electrode, a negative electrode, and a separator into an aluminum or aluminum alloy case, installing a cap plate on the case, injecting electrolyte into the case, and sealing the case. While the case may be made of iron, an aluminum or aluminum alloy case may be lighter and have improved anti-corrosive properties, even when used at high voltages for extended durations.
With a metallic case, the case may function as an electrode and cause a short circuit with another electrode. Even when the case is insulated from both electrodes and the electrodes are separately extracted from the case, the case may make internal contact with both electrodes to cause a short circuit between the electrodes.
Generally, when a bare cell sealed in a can-type rechargeable battery is coupled with a protection circuit module, which may include a positive temperature coefficient (PTC) element, a thermal fuse, a protection circuit board, or other safety features, the bare cell is stored in a hard case or molded by using a hot-melt resin.
The connection between the bare cell and the protection circuit module is made by connecting each electrode terminal of the bare cell to the corresponding electrode terminal of the protection circuit module on the protection circuit board. Thus, electrical coupling between the bare cell and the protection circuit module is emphasized. However, the mechanical strength of the coupling between the bare cell and the protection circuit module has not been emphasized. To improve the mechanical strength of the connection, the bare cell and the protection circuit may be put into a mold, and a fusion resin is filled into the space between them. Alternatively, they each may be inserted into a hard case.
However, when the latter method is used, the hard cases are coupled together, which increases the manufacturing time and cost required to fabricate the rechargeable battery. Additionally, even when the former method is used, pouring resin into the mold can be difficult. Furthermore, the contact between the molded resin and the metallic bare cell rarely retains its mechanical strength and may be damaged from torsional or bending forces.